Corrosion inhibitor for lubricating oils



Patented May 23, 1944 2,349,785 v CORROSION mnmrrgg ron LUBRICATING Jacob Faust. Belleville, N. J., assignor to L. Sonneborn Sons. Inc.. a corporation of Delaware No Drawing. Application July. 15, 1943,

Serial No. 494,837

Claims. (Cl. 252-395) This invention relates to new and useful improvements in corrosion inhibitors for lubricating oils.

Certain lubricating oils although characterized by satisfactory lubricity have yet corrosive properties that impair their general usefulness. These corrosiveproperties are particularly exerted upon metal surfaces and specifically upon bearing surfaces such as those of the cadmiumsilver or copper-lead type. This is especially true of certain types of paraffin base oils as, for instance, Pennsylvania grade oils which have superior lubricating qualities but are relatively corrosive with respective to metal surfaces, and specifically the aforementioned bearing surfaces. This corrosive action seems to be enhanced in the presence of iron compounds.

This problem is overcome by using a lubricating oil normally corrosive to cadmium-silver and copper-lead bearings but containing a small amount of the product obtained by reacting an alkali or alkaline earth mahogany sulphonate with phosphorus penta sulphide.

The phosphorus penta sulphide reacted alkali petroleum mahogany sulphonate may be obtained by treating an alkali or alkaline earth mahogany petroleum sulphonate, such as a Na-, K-, Ca-, Ba-, Mir-mahogany petroleum sulphonate in a suitable aromatic solvent of the benzol series, such as toluol. xylol, or the like, with from 5 to 50%, and preferably 5 to 30%, of phosphorus penta sulphide, at an elevated temperature of for instance between about 175 and 350 F. preferably under reflux conditions. The product thusly obtained may be incorporated in a lubricating oil to produce concentrations ranging from .05 to 1.0%.

When proceeding in this manner, however, the period necessary for satisfactory completion of the reaction is relatively long, and the reaction mass normally requires subsequent filtration in order to remove decomposition products and unreacted agents, including phosphorus trisulplrfde. unreacted phosphorus penta sulphide, sulphur, etc. The uneconomical and time and labor consuming aspects of this procedure are still further disadvantageously affected by the nccessi-y for solvent removal, such as by distillat'on, and the necessity for the application of relatively high temperatures, 1. e., temperatures in excess of the refiux temperatures of the solvents used in order to remove the last traces of thes so!- vents. A certain amount of decomposition is incurred by reason of the relatively h gh solvent removal temperatures and relatively heavy foam formation is encountered, interfering with the satisfactory working up of the final product. Furthermore, the products obtained when proceeding as aforesaid are generally characterized by a relatively high acidity, of for instance an order of acidity equivalent to about mg. KOH per g. reaction product.

I have discovered an improved procedure by which the foregoing disadvantages are substantially overcome and which results in an improved product of decreased acidity.

In accordance with my invention an alkali or alkaline earth mahogany petroleum sulphonate. such as a Na-, K-, Ca-, Ba-, Mg-mahogany petroleum sulphonate is reacted in a hydrocarbon oil solution with from 5 to 50%, and preferably 5 to 30% of phosphorus penta sulphide, at a temperature in excess of 350 F. and below the decomposition temperature of the oil, and preferably between 375 and 400 F. The heating is continued until the completion of the reaction, which is normally evidenced by the cessation of the evolution of H2S. In most cases the reaction is completed within one hour.

Petroleum mahogany sulphonates are obtained in the conventional manner in the sulphuric acid refining, and preferably fuming sulphuric acid or sulphuric anhydride refining of petroleum distillates. As is well known and understood in the art, when so refining such distillates, an oil layer and an acid sludge layer are obtained. The former contains mahogany petroleum sulphonic acids which are essentially oil soluble and water insoluble and constitute a rather complex product. These mahogany sulphonic acids may then be converted into the alkali or alkali earth salts by suitable neutralization of the oil layer containing the acids. They may be recovered by extraction with suitable solvents as for instance aqueous alcoholic solutions.

As a rule, mahogany petroleum sulphonates are obtained in a form containing approximately 20 to 50% of retained or occluded oil. If desired or expedient, the mahogany petroleum sulphonates may be freed from their oil content by conventional extraction methods.

The hydrocarbon oil that may be used in the practice of my invention is preferably a hydrocarbon oil of the viscous petroleum lubricatin oil range. The hydrocarbon all should be of the substantially saturated, i. e., non-olefinic type. and preferably encompasses a viscosity range of from 45 to Saybolt at 210 F. If desired. though not necessary, the hydrocarbon oil may be the same or of the same type as that to which the final phosphorus penta sulphide reacted product is to be added. Suitable illustrative hydrovania and Mid-Continent oils, as well as solvent ramnates from western or gulf coast crudes.

In the practical operation of my invention, a

suitable petroleum mahogany sulphonate, either as such or containing occluded oil, is dissolved in the hydrocarbon oil and the solution then subjected to the reaction temperature. Upon completion of the reaction, the resulting product is in its final form. No filtration or solvent removal is necessary and the ultimate product has a surprisingly low acidity, thus permitting the use of much smaller amounts of neutralizing agents than would be otherwise necessary. As stated, the reaction period is now one hour as contrasted with reaction periods of from 12 to 24 hours in the practice of the aromatic solvent reflux method of said co-pending application.

Within the preferred embodiment of myinvention I find it advisable to use concentrations of petroleum mahogany sulphonate in hydrocarbon oil equivalent to about to 50% solutions, depending upon the viscosity of the oi1 in which the reaction is conducted.-

as aluminum stearate, usually employed in waxcontaining lubricating oil compositions to depress the normal, relatively high pour point thereof. This is for instance demonstrated by the following Tables I and II, giving the corrosion data obtained in accordance with the well known Catalytic Indiana'oxidation test showing loss of weight of cadmium-silver and copperlead bearings respectively subjected to a Pennsylvania SAE 10 oil alone and containing 0.126% aluminum stearate:

TABLE I (Cadmium-silver bearings) Mill 1 t Milli l t i Milligrams r o s y igrams 0s grams 05 n presence 0 Number of hours g g SAE 10 oil+ presence of 0.5% of reaction prod SAE 10 011 0.126% A1 ofreaction product (SAE 10 eil+ stearate uct (SAE 10 oil) 0.326% Al steer- TABLE 11' (Copper-lead bearings) Milligrams] t Milli l t Milligrams 1 5;

os grams os in presence 0 0. Number of hours g' SAE 10 011+ presence of 0.5% or reaction prod' SAE 10 on 0.126% A1 of reaction product (SAE 10 oil-{- stearate) uct (SAE 10 oil) 0.126% A] steerate) 19 57 1 2 Non 55 74 1 I4 29 e 75 90 1 +4 38 95 118 1 +4 38 Represents gain in weight indicating formation of protective film which prevents corrosion.

' The following example is furnished by way of illustration and not of limitation:

EXAMPLE 1 parts by weight of sodium mahogany petroleum sulphonate are dissolved in '70 parts by weight of an SAE Pennsylvania lubricating oil and 12 parts by weight of phosphorus penta sulphide are thoroughly admixed with the solution, whereupon the mix is then heated to about 380 F. After maintaining this temperature for one hour the reaction is completed, resulting in a black, viscous, homogeneous product,. free of sediment or H28 odor. The acidity of the reaction product is equivalent to about20 mgs. KOH per gram. The product is washed with 10% by volume of water containing slightly in excess of the calculated quantity of caustic soda to neutralize the acidity present. The aqueous caustic layer is permitted to settle out and the reaction product is then heated to 240-F. to drive out the retained moisture.

It will be noted from the above tables I and II that the loss in weight of both cadmium-silver and copper-lead bearings remains static after 48 hours oxidation. This is highly significant inasmuch as it indicates that the phosphorus penta sulphide reacted mahogany sulphonate prepared in accordance with my invention is capable of imparting to a lubricating oil compounded therewith a flat oxidation curve in contrast to a constantly rising oxidation curve characteristic of oils compounded in accordance with said herein first mentioned procedure when tested underthe same conditions.

The tendency for the formation of corrosive substances may'also be measured by what is generally referred to as a corrosion induction period. This represents the period of time within which a test piece, such as a cadmium-silver or copper-lead hearing, when immersed in a lubricating oil at a standard elevated temperature (300 to 350 R), will remain substantially unaflected, i. e., will show substantially no loss in weight.

When subjecting a lubricating oil composition containing phosphorus penta sulphide reacted alkali or alkaline earth mahogany petroleum sulphonate prepared in accordance with my invention to induction period tests, considerably higher induction periods are exhibited than are possessed by lubricating oil compositions compounded in accordance with the said co-pending application tested under identical conditions and containing comparative concentrations of reaction product. Thus for instance a Pennsylvania SAE oil containing 0.5% of phosphorus penta sulphide reacted sodium mahogany petroleum sulphonate obtained in accordance with Example I possesses an induction period of approximately parts by weight of calcium mahogany petroleum sulphonate are dissolved in 70 parts by weight of an SAE Gulf Coast solvent refined lubricating oil and 12 parts by weight of phosphorus penta sulphide are thoroughly admixed with the solution. The same procedure is then followed in working up to the final product as set forth in connection with Example I.

The foregoing specific description is for purposes of illustration and not of limitation and it is therefore my intention that the invention be limited only by the appended claims or their equivalents wherein I have endeavored to claim broadly all inherent novelty.

GEn'lIFICATE Patent'No. 2,5 t9,785.

I claim:

1. Method of preparing a corrosion inhibitor for compounding with a lubricating oil normally corrosiv to cadmium-silver and copper-lead bearings, which comprises reacting a mahogany petroleum sulphonate selected from the group consisting of alkali and alkaline earth metal mahogany petroleum sulphonates in solution in a petroleum hydrocarbon oil of the lubricating oil series with phosphorus penta sulphine until completion of the reaction.

2. Method in accordance with claim 1, in which said mahogany petroleum sulphonate is present in said hydrocarbon oil in from 10 to concentration, and in which said reaction is carried out at a temperature in excess of 350 F. and below the decomposition point of said hydrocarbon oil.

3. Method of preparing a corrosion inhibitor for compounding with a lubricating oil normally corrosive to cadmium-silver and copper-lead bearings, which comprises reacting a mahogany petroleum sulphonate selected from the group consisting of alkali and alkaline earth metal mahogany petroleum sulphonates in from 10 to 50% solution in a petroleum hydrocarbon lubricating oil 01 between 45 and Saybolt viscosity at 210 F., with 5 to 30% phosphorus penta sulphide at a temperature between 375 an i 400 F.

4. Method in accordance with claim 3, in which said mahogany petroleum sulphonate is alkali metal mahogany petroleum sulphonate.

5. A corrosion inhibitor for compounding with a lubricating oil normally corrosive to cadmiumsilver and copper-lead bearings, which essentially comprises the reaction product derived from the phosphorus penta sulphide reaction in petroleum hydrocarbon oil solution of a petroleum mahogany sulphonate selected from the group consisting of alkali and alkaline earth metal mahogany petroleum su1phonates..

0F CORRECTION.

May 5: 9 4 1 JA CO B FAUST It is hereby certified that error. appears in the printed specification of the above numbered patent requiring correction as follows: Page 5, first column, line 1b., after the word. "containing" insert "about"; and second column, line 10, claim 1, for "s lphine'" read --sulphide-- should be read th this correction therein that the said Letters Patent and that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 8th day of August, A. D. 19bi (Seal) Leslie Frazer Acting Commissioner of Patents.

CIsni'IFIGATE OF CORRECTION. P mhmss. my 5, 19 m.

JACOB FAUST.

It is hereby certified that error appears in the printed specification of the above nuinbered patent requiring correction as follows Page 5, first column, line 11;, after the word "containing" insert about---; and second column, line 10, claim 1, for "sulphine" read --sulphide--; and that the said Letters Patent should be ead with' this correction therein that the same may conform to the record of the case in the Patent Office.

Signed. and sealed this 8th day of August, A. D. 191 1;.

Leslie Frazer (Seal) Acting Commissioner of Patents. 

